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Aurantii Amari Cortex, Bitter Orange Peel; Aurantii Cortex Indicus, Indian Orange Peel; Aurantii Cortex R

Aurantii Amari Cortex. U. S. (Br.)

Bitter Orange Peel. Aur. Amar. Cort.

Preparations: Orange Flower Water - Stronger Orange Flower Water - Oil of Orange - Compound Spirit of Horseradish
Related entry: Lemon

"The dried rind of the fruit of Citrus Aurantium amara Linne (Fam. Rutaceae)." U. S. " Dried Bitter-Orange Peel is the dried outer part of the pericarp of Citrus Aurantium, var. Bigaradia, Hook. f." Br.

Aurantii Cortex Siccatus, Br.; Aurantii Pericarpium; Cortex Aurantiorum, Cortex Pomorum Aurantii; Seville Orange Peel, Wild Orange Peel; Ecorce (Zeetes) d'Oranges ameres, Ecorce de Bigarade, Fr.; Cortex Aurantii Fructus, P. G.; Pomeranzenschale, G.; Corteccia di arancio amaro, It.; Corteza de naranja amarga, Sp.

Bitter Orange Peel of the U. S. P. IX is the dried rind. In the Br. Pharm., 1914, both the dried and the fresh rind are official, while under the name of Aurantii Cortex Indicus, Indian Orange Peel, the British Pharmacopoeia, 1914, recognizes the bitter orange peel obtained from varieties of the Citrus Aurantium, grown in India and Ceylon. For description and properties, see under Aurantii Dulcis Cortex.

Off. Prep.—Fluidextractum Aurantii Amari, U. S.; Infusum Aurantii, Br.; Infusum Aurantii Compositum, Br.; Tinctura Aurantii Amari, U. S. (Br.); Syrupus Aurantii (from Tincture), Br.; Vinum Aurantii Compositum, N. F.


Aurantii Cortex Indicus. Br.

Indian Orange Peel

"Indian Orange Peel is the fresh and the dried outer part of the pericarp of varieties of Citrus Aurantium, Linn., grown in India and Ceylon." Br.

It is thus described: "Possesses the pleasant aromatic odor and bitter taste characteristic of Bitter-Orange Peel derived from Citrus Aurantium, var. Bigaradia, Hook, f. Inner surface retains not more than a very small amount of the white spongy part of the pericarp." Br.

In India and the Eastern divisions of the Empire, Indian Orange Peel, fresh or dried, may be employed in making the official preparations for which Fresh or Dried Bitter-Orange Peel is directed to be used.


Aurantii Cortex Recens. Br.

Fresh Bitter-Orange Peel

"Fresh Bitter-Orange Peel is the fresh outer part of the pericarp of Citrus Aurantium, var. Bigaradia, Hook. f." Br.

It is thus described: "Outer surface red or deep orange-red in color, and generally rough. Inner surface retains not more than a very small amount of the white spongy part of the pericarp; in transverse section numerous large oil-glands below the epidermis. Pleasant aromatic odor; taste aromatic, bitter." Br.


Aurantii Dulcis Cortex. U. S.

Sweet Orange Peel. Aurant. Dulc. Cort.

"The outer rind of the fresh, ripe fruit of Citrus Aurantium sinensis Gallesi (Fam. Rutaceae)." U.S.

Cortex Aurantiorum Dulcium; Ecorce (Zestee) d'Oranges douces, Fr.; Apfelsinenschalen, G.; Scorze del frutto dell' arancio, It.; Corteza de naranja dulce, Sp.


The U. S. Pharmacopoeia includes two kinds of orange peel, bitter and sweet, the former dried and the latter fresh. On the other hand, the British Pharmacopoeia recognizes bitter orange peel in three forms, the fresh and the dried, under the respective names of Aurantii Cortex Recens, fresh bitter orange peel, Aurantii Cortex Siccatus, dried bitter orange peel, and Indian Orange Peel; but the orange peel which is called sweet by the U. S. Pharmacopoeia—i.e., Citrus Aurantium—is termed C. Aurantium var. Bigaradia, bitter orange peel, by the British authority.

The orange tree grows to the height of about thirty feet. Its stem is rounded, much branched, and covered with a smooth, shining, greenish-brown bark. In the wild state, and before inoculation, it is often furnished with axillary spines. The leaves are ovate, pointed, entire, smooth, and of a shining pale green color. When held between the eye and the light, they exhibit numerous small transparent vesicles, filled with volatile oil, and when rubbed between the fingers, are highly fragrant. Their footstalks are about an inch long, and have wing's or lateral appendages. The flowers, which have a delightful odor, are large, white, and attached by short peduncles, singly or in clusters, to the smallest branches. The calyx is saucer-shaped, with pointed teeth. The petals are oblong, concave, white, and beset with numerous small glands. The filaments are united at their base in three or more distinct groups, and support yellow anthers. The ovary is roundish, and bears a cylindrical style, terminated by a globular stigma. The fruit is a spherical berry, often somewhat flattened at its base and apex, rough, of a yellow or orange color, and divided internally into a number of vertical loculi, each containing from two to four seeds, surrounded by a pulp. The rind of the fruit consists of a thin exterior layer, abounding in schizolysigenous cavities filled with a fragrant volatile oil, and of an interior one, which is thick, white, spongy, insipid, and inodorous.

According to Lloyd, the orange was unknown to the ancient Greeks and Romans and was probably introduced into Europe by the Arabians. (Bull. Lloyd Libr., 1911, p. 7.) According to Tschirch, the word orange is derived from the Sanscrit, Nagaranga or Naranga. (J. P. C., 1910, p. 2.)

There are two varieties of C. Aurantium, considered by some as distinct species. They differ chiefly in the fruit, which in one is sweet, in the other is sour and bitterish and often has a darker and rougher rind. The sweet is officially recognized as Citrus Aurantium sinensis L., and the bitter or Seville variety as Citrus Aurantium amara L. The latter is ascribed by the British authority to Citrus Aurantium var. Bigaradia Hook, f., which is the Mandarin Orange. This is probably a native of China, but cultivated in Sicily, the south of Italy, and Florida, bears a fruit much smaller than the common orange, round, but flattened above and below, with a smooth, thin, delicate rind, and a very sweet delicious pulp. A volatile oil is obtained from the rind by expression, of a yellow color, a very bland agreeable odor, different from that of the orange or lemon, and a not unpleasant taste, like that of the rind. When freed from coloring matter by distillation, it was found by M. S. de Luca to be a pure hydrocarbon, with the formula C10H16. (J. P. C., 3e ser. xxxiii, 52.) This constituent is now recognized as d-limonene.

The orange tree is a beautiful evergreen, in which the fruit is mingled, in every stage of its growth, with the blossoms and foliage and has been applied to numerous purposes of utility and ornament. A native of China and India, it was introduced into Europe at a very early period, was transplanted to America soon after its first settlement, and is now found in every civilized country where the climate is favorable. The fruit is brought to us chiefly from California, Florida, Southern Europe, and the West Indies. The Florida and Havana oranges are the sweetest. A seedless variety termed the navel orange is rapidly replacing all others in cultivation.

Various parts of the plant are used medicinally. The leaves, which are bitter and aromatic, are employed in some places in the form of infusion as a gently stimulant diaphoretic. They yield by distillation with water a volatile oil, which is said to be often mixed by the distillers with the oils obtained from the flowers and unripe fruit. In regard to polarized light it has a rotary power to the left, which is considerably weakened by the prolonged action of heat. (Chautard, J. P. C; 3e ser. xliv, 28.) The fresh flowers may be kept for some time by mixing them well with half their weight of sodium chloride, pressing the mixture in a suitable jar, and keeping it well closed in a cool place. They were formerly recognized by the U. S. P. under the name of Aurantii Flores, and were officially described as " about half an inch (12 mm.) long; calyx small, cup-shaped, five-toothed; petals five, oblong, obtuse, rather fleshy, white and glandular-punctate; stamens numerous, in three or more sets; ovary globular, upon a small disk, with a cylindrical style, and a globular stigma; odor very fragrant; taste aromatic and somewhat bitter." U. S., 1880. The dried flowers are used on the continent of Europe as a gentle nervous stimulant, in the form of infusion, two drachms to the pint of boiling water, taken in the dose of a teacupful. The flowers should be dried in the shade, at a temperature between 24° C. (75° F.) and 35° C. (95° F.).

An oil is obtained also from the flowers by distillation,, which is called oil of neroli, and is much used in perfumery, and in the composition of liqueurs. It is an ingredient of the famous Cologne water. That obtained from the flowers of the Seville or bitter orange is deemed the sweetest. It was introduced into the Edinburgh Pharmacopoeia, with the title of Aurantii Oleum, to serve for the preparation of orange flower water. Soubeiran considers this oil rather as a product of the distillation than as pre-existing in the flowers. The fact may thus be explained that orange flower water made by dissolving even the finest neroli oil in water has not the precise odor of that procured by distillation from the flowers.

The fruit is applied to several purposes. Small unripe oranges, about the size of a cherry or less, previously dried, and rendered smooth by a turning-lathe, were sometimes employed to maintain the discharge from issues. They were preferred to peas on account of their agreeable odor, and by some were thought to swell less with the moisture; but this was denied by others, and it was asserted that they required to be renewed at the end of twenty-four hours. These fruits are sometimes found in commerce under the name of orange berries. They are sub-globular, 5 to 20 mm. in diameter, of a grayish or greenish-brown color, fragrant odor, and bitter taste, and are said to be used for flavoring cordials. A volatile oil is obtained from them by distillation, known to the French by the name of essence de petit grain, and employed for similar purposes with that of the flowers. The oil, however, which now goes by this name is said to be distilled from the leaves, and those of the bitter orange yield the best. The oils from the unripe and the ripe fruit have a rotating power to the right, the latter much greater than the former; and this property might serve to distinguish them from the oil of the leaves. Several of the oils from the Rutaceae deposit a crystalline substance, differing from camphor. (Chautard.) The juice of the Seville orange is sour and bitterish, and forms with water a refreshing and grateful drink in febrile diseases. It is employed in the same manner as lemon juice, which it resembles in containing citric acid, though in much smaller proportion. The sweet orange is more pleasant to the taste, and is extensively used as a light refrigerant article of diet in inflammatory diseases, care being taken to reject the membranous portion. The best mode of separating the outer rind, when its desiccation and preservation are desired, is to pare it from the orange in narrow strips with a sharp knife, as we pare an apple. When the object is to use the fresh rind for certain pharmaceutical purposes, as for the preparation of the confection of orange peel, it is best separated by a grater, carefully avoiding the grating of the white portion which contains the bitter principle. The dried peel sold in the shops is usually that of the Seville orange, and is brought chiefly from countries adjacent to the Mediterranean.

Properties.—Bitter orange peel has a grateful aromatic odor, which depends upon the volatile oil contained in its schizolysigenous cavities, and a warm, bitter taste. Bitter orange peel occurs "in narrow, thin bands (ribbons), or more often elliptical, flattened, more or less curved, pieces (quarters), varying from 3 to 6 cm. in length; outer surface convex, varying from reddish- or yellowish-brown (ribbons) to greenish-brown (quarters), coarsely reticulate and with the edges recurved; inner surface concave, whitish, with numerous conical projections and yellowish-white, linear, more or less anastomosing fibro-vascular bundles; fracture hard; transverse section light brown, somewhat spongy, outer layer with 1 or 2 rows of oil reservoirs; odor fragrant; taste aromatic and bitter. The powder is yellowish-white or light brown; fragments of parenchyma cells numerous, the walls from 0.004 to 0.012 mm. in thickness; few fragments of tracheae with close spiral markings or simple pores; occasional membrane crystals of calcium oxalate in monoclinic prisms, from 0.02 to 0.035 mm. in diameter. Powdered Bitter Orange Peel is colored yellowish upon the addition of potassium hydroxide T.S. Bitter Orange Peel yields not more than 7 per cent. of ash." U. S.

"In thin strips. Outer surface deep orange-red and rough. Inner surface retains not more than a very small amount of the white spongy part of the pericarp; in transverse section numerous large oil-glands below the epidermis. Pleasant aromatic odor; taste aromatic, bitter." Br.

The Br. Pharmacopoeia requires that the outer surface both of the fresh and of the dried bitter orange peel shall be of a deep orange-red color, and rough and glandular.

The sweet peel is described officially as having "the outer, orange-yellow layer recently separated by grating or paring and consisting of epidermal cells, parenchyma cells of the sarcocarp with chromoplastids, oil reservoirs and globules of volatile oil; odor highly fragrant; taste pungently aromatic." U. S.

For the preparation of powdered bitter orange peel the German Pharmacopoeia directs that the drug should be previously dried over freshly burnt lime. For histological study of orange fruit, see Winton and Moeller, " The Microscopy of Vegetable Foods." Bitter orange peel is sometimes adulterated with sweet orange peel. The latter is distinguished by the pieces being thinner and of a more orange-red color. They are less aromatic and bitter. The following test which is distinctive for bitter orange peel is recognized by the Netherland Pharmacopoeia: the section of the fruit is mounted in a solution of potassium bichromate slightly heated when the tissues become colored brown. This reaction does not take place with sweet orange peel. A distinctive test for the latter is the use of fuming nitric acid (containing 55 per cent. N2O5) which gives a dark green color distinguishing it from bitter orange peel which is colored brown.

Both orange peels yield their sensible properties to water and alcohol. The bitter principle, hesperidin C22H26O12, was discovered by Lebreton in 1828, but its character as a glucoside was first established by Hilger and Hoffmann. (Ber. d. Chem. Ges., 9, 26, 685.) Treated with diluted acids it yields hesperedin, C16H14O6, and glucose. It is crystalline (fusing point 250° to 251° C. (482°-483.8° F.), and may be prepared by Patemo and Briosi's process, as follows: The cut and bruised oranges are covered with diluted alcohol, solution of potassium hydroxide added in excess, the liquor filtered after two days, and impure hesperidin precipitated by hydrochloric acid; the precipitate is boiled with acetic acid for ten minutes, and, after cooling, filtered from the resinous mass left. The hesperidin gradually separates from the filtrate upon standing, in white fine needles. From 4000 oranges about 6 ounces av. of the principle were obtained. (Ber. d. Chem. Ges., 1876, 250-252.) Tanret found in the rind of the bitter orange,

(1) a crystalline acid, C44H28O14;
(2) a non-crystalline resinous body;
(3) hesperidin;
(4) isohesperidin, a crystalline glucoside isomeric with hesperidin;
(5) aurantiamarin, another glucoside to which, in part, the bitterness of the peel is due. (P. J., 1886, 839.)

Orange peel contains also albumen, gum, resin, a trace of fixed oil, volatile oil, and a principle resembling tannin in its action on salts of iron. The bitter principles are much more abundant in the white spongy inner portion of the peel than in the outer yellowish layer. The volatile oil, Oleum Aurantii, U. S., may be obtained by expression from the fresh grated rind, or by distillation with water. It is imported into the United States in tinned copper cans. It has properties resembling those of the oil of lemons, but spoils more rapidly on exposure to the air, acquiring a terebinthinate odor. The perfumers use it in the preparation of Cologne water, and for other purposes; and it is also employed by the confectioners. According to Imbert-Gourbeyre, persons who are much exposed to the inhalation of the oil of bitter oranges are apt to be affected with cutaneous eruptions, and various nervous disorders, as headache, tinnitus aurium, oppression of the chest, gastralgia, want of sleep, and even muscular spasm. (Ph. Ch., Feb., 1854, 128.)

Uses.—Bitter orange peel is a mild tonic, carminative, and stomachic; the sweet is simply aromatic; but neither is much used alone. They are chiefly employed to communicate a pleasant flavor to other medicines, to correct their nauseating properties, and to assist their stimulant impression upon the stomach. They are a frequent and useful addition to bitter infusions and decoctions, such as those of gentian, quassia, calumba, and Peruvian bark. It is obviously improper to subject orange peel to the action of heat, as the volatile oil is thus driven off. Violent colics, convulsions, and even death have been caused in children by eating large quantities of the rind. When orange peel is used simply for its agreeable flavor, the rind of the sweet orange is preferable; as a tonic, that of the Seville orange.

Dose, from half a drachm to a drachm (2.0-3.9 Gm.).

Off. Prep.—Syrupus Aurantii, U. S., Br. (from Tincture); Tinctura Aurantii Dulcis, U. S.; Vinum Aurantii (from Fresh Peel), Br.


The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.



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